Question

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

1. What is metal M?
2. What is solution S? Is it acidic or alkaline?
3. What is gas G?
4. Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
5. Is this reaction exothermic or endothermic?

Answer 1

1. Metal M is sodium (Na), which is used as a coolant in nuclear reactors.
2. Solution S is a sodium hydroxide solution (NaOH). It is alkaline; it turns red litmus to blue.
3. Gas G is hydrogen gas, which is lighter than air.
4. \[\ce{2Na_{(s)} + 2H2O_{(l)} -> 2NaOH_{(aq)} + H2_{(g)} + HEAT}\]
5. This reaction is exothermic because it releases excessive heat.